Projection apparatus



A. AMES, JR.-

PROJECTIO-N APPARATUS. APPLICATION FILED OCT. 11, 1916.

1,376,913 v Patented May 3,1921.

. shown in Fig. 3; and

UNITED STATES OFFIQ PROJECTION APPARATUS.

Specification of Letters Patent.

Patented May 3, 1921.

Application filed October 11, 1916. Serial No. 125,109.

and below a horizontal direction without.

projecting substantially any light upwardly. The principalobject of the invention is to provide apparatus in which alight source having a substantial vertical dimension, for example,a gas flame, is employed, which is adapted to project a comparatively concentrated beam of light horizontally without projecting-substantially any light upwardly. Other objects of the invention will be ap parent from the following description and the accompanying drawings, in which- Figure 1 is a vertical longitudinal sec- 1 tion of one embodiment of the invention; Fig. 2 is a front elevation of the apparatus illustrated in Fig.1;

Fig. 3 is an enlarged side GlQVLtlOIl of one formof light source;

Fig. 4 isa rearelevation of the apparatus Fig. 5 is a top plan view of the apparatus shown in Fig. 3.

The apparatus illustrated in Fig. 1 1s similar to the ordinary acetylene headlight which is divided vertically into two spaced parts with the light source positioned between the two parts. This apparatus differs from prior headlights however, in the shaping and positioning of the various portions of the reflecting surface. The paraboloidal reflector P is positioned in the rear of the light source and extends forwardly to a vertical plane disposedslightly in the rearof the light source, and has its focus 7, dis

posed substantially at the base of the gas flame 11. The reflector 1? which is illustrated as being paraboloidal, has its focus at f, in the rear of the light source and at the 1 point of intersection of the axis of the reflector and the light line 12 passing through the central point 13 of the forward edge of the reflector P and the. uppermost point of the light source 11. The re-- flector P, extends downwardly to the hor1- zontal plane containing the axis of the apparatus where it is joined to the lower paraboloidal reflectorl by means of horizontal members 14. The reflector P is also preferably paraboloidal and preferably has its focus f disposed in front ofthe light source at the point of intersection of the axis of the reflector and the line 16 passing through the uppermost point of the light source and the central point 17 of the forward edge of thereflector P The light source may comprise the ordinary ll-shaped burner 21. mounted on the supply tube 22, which in turn is supportedbeneath the reflectors as illustrated at 23.

The luminous portion of the flame produced by the ordinary acetylene headlamp has a lower end of irregular outline as repre sented in Fig. l, this being due to the fact that the lower central portion 28 of the flame, which is surrounded by outrushing gas, does not receive sufficient oxygen at this region to form other than a non-luminous blue flame. Therefore, if the reflector disposed rearwardly of the light source has its focus positioned at the extreme lower point 30 of the flame, no light will emanate from the immediate vicinity of the focus and the projected beam consequently will have a hollow or dark portion along the axis of the reflector. Such a beam is unsatisfactory for adequately illuminating distant portions of the roadway and I prefer to avoid this condition by positioning the parts so. that the reflector positioned behind the light source has its focus disposed at the top of the dark portion 28, that is, at f, in Fig. 4.

However, with the focus f so disposed, the lower lateral portions of the luminous flame extend below the horizontal'plane containing the axis of the reflector and, in the absence of preventive means, the light radiating approximately horizontally from the portions of the light source displaced below this plane is reflected upwardly from the portions of the reflector adjacent the plane,

from this cause comprises a member 24E for shielding the portion of the reflector P adjacent the horizontal axial plane from the portions of the light source extending below the plane. The shield 24 is preferably positioned immediately behind the burner and.

be provided "in the shield to receive the rear portion of the burner. For like reasons, the member 24 may have ears 29 111 the form of narrow 'bandsextendlng forwardly on opposite sides of the light source to shield the portions of reflectors P and P lying adj acent the horizontal axial plane from the portions of the light source extending below the plane,'the ears 29 extending forwardly only a sufficient distance to accomplish this purpose. However, instead of employing the ears 29,the reflectors P and P, may be positioned withtheir axes at or below the lowermost points of the luminous flame so that all light striking these reflectors adjacent their horizontal axial plane or planes will be reflected in or below a horizontal direction. The operation of the apparatus is as follows: A11 light striking the lower half of the reflector P, is projected in or below a horizontal direction, as represented by ray 31, inasmuch as substantially the entire light source is positioned above the focus of the reflector so that all light therefrom to the lower portion of the reflector passes in the rear of the focus, and inasmuch as light from the small portion of the light source extending 'below'the focus is obstructed by shield 24. All light striking the upper half of the reflector is incident-as if coming from the focus or from in frontof the focus, and 1s 1 therefore projected either horizontally as represented by ray 32, or downwardly as represented by ray 33. 7

All light striking the reflector P is reflected in or below a horizontal direction in asmuch as all light striking this reflector is incident as if coming from in front of its focus f For example, a ray emanating from the'uppermost point of the'light source and folloWingalong line 12, would strike the central forward edge of the reflector as if coming from thefocus 7",, thereby being reflected'horizontally, and all light radiating from other portions of the light source is reflected 1 downwardly as represented by ra 34.

All light striking reflector P is projected in or below .a horizontal direction inasmuch as all lightstriking the reflector passes rearwardly of its focus i 'F'orexample, a ray emanating from the uppermost point of the light source and following along line 16 through focus, 7, and striking the forward edge of the reflector at 17is projected horizontally, and all rays emanating from other portions of the light source, such as ray 36, necessarily pass'in therear of the focus f, and are therefore projected below the afore said horizontal axial plane.

As above mentioned, when employing a light source extending below the horizontal plane containing the axis of the rear reflector, either the forward reflectors should be positioned with their axes at or below the lowermost points of the luminous source or shields, such as ears 29, should be provided to prevent upward glare due to light radiating from the portions of the light source extending below the horizontal plane containing the axis of the rear reflector and directed approximately horizontally toward the portions of the forward reflectors lying adjacent the horizontal plane or planes containing their axes.

Thus it will be seen that while I employ a light source having substantial, dimensions whereby it cannot be positioned wholly in the focus of the reflector, yet the reflecting surfaces are so disposed that no light is reflected upwardly from the apparatus. Furthermore, owing to the novel disposition of the foci of the various reflecting surfaces the light striking each reflector is incident thereto as if coming from the immediate region of the focus of the surface, so that a relatively concentrated beam of light may be projected substantially horizontally.

It is to be noted that the words above, below, horizontally, upwardly, downwardly, etc. are employed in the specification and claims merely in a relative sense for the sake of convenience and conciseness, and that the apparatus is not limited to use in the sole position and for the sole purpose described.

I claim:

1. Projection apparatus comprising a light source having at least one substantial dimension, a reflector positioned rearwardly of the light source with a portion of its reflecting surface on each side of a horizontal plane through the light source, and a reflector positioned forwardly of the light source with a portion of its reflecting surface on each side of said plane, the two reflectors being shaped and positioned with their foci axially spaced apart and with the focus of the rear reflector substantially in the light source, so that light is projected in and below a horizontal direction without projecting substantially any light upwardly.

2. Projection apparatus comprising a light source having at least one substantial dimension, a single focus reflector so positioned rearwardly of the light source, with portions disposed on opposite sides of a horizontal plane through the region of the light source, so as to reflect light horizontally, a reflector positioned forwardly of the light source and above saidhorizontal plane with its focus rearwardly of the light source, and

a reflector positioned forwardly of the light source and below said horizontal plane with its focus forwardly of the light source.

3. Pro ection apparatus comprising a light source having a substantial vertical dimension, a reflector extending continuously above and below a horizontal plane through the region of the light source and being positioned rearwardly of the light source so as to reflect light in and below a horizontal direction without reflecting substantially any light upwardly, a reflector positioned forwardly of the light source and above said horizontal plane with its focus rearwardly of the light source, and a reflector positioned forwardly of the light source and below said horizontal plane with its focusforwardly of the light source, whereby a concentrated beam of lightmay be projected horizontally without producing upward glare.

4. Projection apparatus comprising a light source having a substantial vertical dimension, a reflector positioned rearwardly of the light source with its focus at the base of the light source, a reflector positioned upwardly and forwardly of the light source with its focus rearwardly of the light source and a reflector positioned downwardly an forwardly of the light source with its focus forwardly of the light source.

5. Projection apparatus comprising two reflectors horizontally spaced apart, a light below a horizontal direction, and means for preventing light from the portions of the light source disposed below. the respective axes from being reflected upwardly from the portions of the reflectors lying adjacent the horizontal plane or planes containing the said axes.

Signed by me at Boston, Massachusetts, this third day of October, 1916.

ADELBERT AMES, J R. 

